Taurine is present in high concentrations in retina; it is mainly localized at the photoreceptors and experimental evidence has suggested its involvement in photoexcitation. Taurine has also been proposed to be an inhibitory neurotransmitter in retina. We have considered the possibility of an involvement of taurine in a common mechanism underlying both, photoexcitation at photoreceptors and synaptic transmission. This action of taurine might be mediated through an effect on mechanisms regulating calcium redistribution. We have observed that in physiological medium, taurine affected calcium accumulation by retinal subcellular fractions and the purpose of the present work will be the characterization of the calcium transport system (s) affected by taurine. The localization of these mechanisms at the intraretinal structures, the mode of action of taurine and if possible, its physiological relevance will be explored. Through its action on calcium fluxes, taurine might be related to contractile processes occurring in retina, at photoreceptors as well as at synaptic levels, to stablilizaton of elements of the cytoskeleton or in membranes in photoreceptors, or to a neuromodulator role, modifying neurotransmitters release. Taurine effects on these retinal functions will be examined.